1. Field of the Invention
The present invention relates to a communication system, and more particularly, to a wireless local loop system.
2. Background of the Related Art
A wireless local loop system (WLL) provides wireless subscriber lines between subscribers and a switching center. The WLL system can provide voice communication services, facsimile services, and data communication services.
FIG. 1 illustrates a related art separate type and integrated type WLL system. Referring to FIG. 1, the WLL system is provided with a stationary telephone set 10 installed in a home or office, a WLL wireless access device 20 connected to the stationary telephone set 10 for transmitting and receiving information over a wireless interface, and an integrated type WLL terminal 30 having a WLL wireless access device built therein. The WLL system further includes base stations 40 for accessing the WLL wireless access device 20 or the integrated type WLL terminal 30, a base station controller 50 connected to the base station by wire for processing a call and transmitting a message, and a managing device 60 for managing and maintaining the WLL system. Finally, a switching center 70 is connected to the base station controller 50.
An operation of various parts of the foregoing WLL system will next be described.
The WLL wireless access device 20, provided at an end point of the WLL system, transmits and receives information over a wireless interface. The wireless access device further transmits a signal converted from a radio frequency signal into a base band signal to a subscriber, and transmits a signal converted from a base band signal into a radio frequency signal to a base station 40. The wireless access device also processes a protocol signal for a communication network, and processes a voice signal.
The base station 40 accesses the WLL wireless access device 20 by a wireless WLL terminal, or an integrated type WLL terminal 30 having the WLL wireless access device 20 built therein. The base station 40 also processes a radio frequency signal, to modulate or demodulate the radio frequency signal. The base station 40 further performs channel encoding and decoding on the modulated or demodulated signal. The base station 40 accesses the base station controller 50 through a particular trunk E1/HDSL by wire.
The base station controller 50 is positioned between the base station 40 and the switching center 70, and controls a number of base stations 40. The base station controller 50 transmits a signal, processes a call, transforms a code, and interfaces with the base station 40 and the switching center 70.
The managing device 60 manages and maintains the WLL wireless access device 20, the base stations 40, and the base station controller 50. This is performed using a function for managing a network system, a function for managing network elements, a function for managing performance, a function for processing a data, a function for managing by software, and a function for managing security.
In the foregoing WLL system, when the WLL terminal 30 is off-hook, an origination message is at once provided from the WLL terminal 30 to the base station 40, to initially assign a communication channel (or traffic channel) for the terminal 30 by the base station 40. If a digit(s) is dialed, the digit(s) is temporarily stored, and then transmitted to the base station 40 after the traffic channel is assigned. Each of the digits provided after the traffic channel is assigned is sequentially transmitted to the base station 40 whenever the digit is provided.
The base station 40 receives a dual tone multiple frequency (DTMF) message inclusive of the provided digit information from the terminal 30, analyzes a telephone number based on the DTMF message, and connects a destination terminal and an origination terminal 30.
The related art WLL system has various problems. For example, the processing of all of the digits from the subscriber at the base station 40 causes an overload on the base station 40.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.